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Variable PWM Frequency

RC4 Series 3 devices support a wide range of pulse-width-modulation (PWM) frequencies.  PWM provides the smoothest LED dimming available, but can cause banding and other artifacts when captured with video recorders.  Lower PWM frequencies, down to the low hundreds of Hz, look best to the human eye and are favored for theatrical and other live entertainment applications.  Higher PWM — 5kHz and up — eliminates video artifacts.

RC4 Wireless provides the widest range of PWM frequencies available on the market: 77Hz, 615Hz, 1250Hz, 5kHz, 10kHz, 20kHz, and 40kHz.  At the top of the range, super-slow-motion (very high frame rate) video is flicker-free.



Using common PWM dimming near electrified musical instruments and microphones can result in audible interference.  This is because 77Hz, 615Hz, 5kHz, and 10kHz are all audible frequencies, and audio circuitry can be exceptionally sensitive to electromagnetic interference.  The solution for this is 20kHz and 40kHz PWM.  These very high modulation frequencies deliver lower resolution, not high enough to completely eliminate “steppiness” at the bottom of the ISL curve when dimming LEDs.  Nonetheless, this trade-off is entirely acceptable when clean, clear, crisp audio is paramount.

The selected frequency will be used whenever an ISL curve is assigned using either RC4MagicPC or RC4 OneTouchTM.  If you will routinely be using your RC4 Series 3 dimmer with video, leave the PWM frequency at 5kHz.  If you are always lighting instruments and microphones, leave it at 20kHz.  Be sure to switch back to 615Hz in live performance situations to deliver the best appearance for human observers.

The PWM frequency setting is stored and remembered forever until you change it or restore default settings.  Factory default is 615Hz.